Tabora Girls Secondary School reduces its carbon footprint through the use of bio-latrines

Oct 24, 2016

Established 88 years ago, with an enrolment of 717 students, Tabora Girls Secondary School has been heavily relying on grid electricity for lighting, and firewood for heating and lighting consuming about 84,000 kg per month at a cost of TZS 3.36 million or 1,008,000.00 kg spending about TZS 40.32 per year. The situation would, however, change when Mr. Mathias Lubatula, the Second Master at the school, learnt about the bio-latrine technology at a workshop that was held in favour of the Global Environment Facility (GEF) and the United Nations Development Programme (UNDP) project titled Mainstreaming Sustainable Forest Management (SFM) into the Woodlands of Western Tanzania, which covers Tabora and Katavi administrative regions.

Following the workshop, the project and the school agreed to install a bio-latrine of 20 cubic meters for demonstration purposes with a view that other institutions (schools, hospitals, prisons, etc.) would adopt the technology, if successful. Bio-latrines use a dry toilet technology which reduces the demand for water. The bio-latrine includes a natural exhausting process so that the digester system never fills up to overflow. The waste collected in the digester is processed using anaerobic digestion to make organic manure (suitable for use as fertiliser). As the waste biodegrades, the digester captures methane gas which is used for lighting and cooking. During construction, the school allowed the project to convert one of its pit latrines into a bio-latrine.

Commissioned in June 2015, the bio-latrine has now been operational for a year, during this period it produces enough gas for cooking for 2 hours, and lighting for 4 hours per day. This has led to reduction of 1/3 in firewood consumption to 56,000 kg per month or 672,000 kg per year. This reduction in firewood consumption has led to concomitant led to a saving of TZS 1.12 mil per month or TZS 13.44 mil per year, which is more or less the amount spent on installing the bio-latrine, implying that the school could literary fund a new bio-latrine thereby reducing the consumption of firewood further. “The savings are, however, spent on repairing and maintaining the plant, producing more vegetables for the school (instead of buying from the market), and buying tree seedlings for planting on bare ground as environmental as part of conservation”, so say Mr. Lubatula.

The bio-latrine is not without challenges. “Some students bath in the bio-latrine, the soap affects the anaerobic digestion of the system. Also, insufficient water flowing into the bio-latrine to sufficiently dissolve the waste. “I repair the water infrastructure in order to solve the problem of water, and restrict students from bathing in the bio-latrine” says Mr. Lubatula who would like the project fund a second bio-latrine because besides the monetary savings, the technology is also better for the health of the cooks and students, who are no longer exposed to smoke as much as was the case before the kitchen started using biogas from the bio-latrine for cooking.

Notwithstanding the challenges, the most enduring benefit of the bio-latrine is that the school has reduced its carbon footprint. Before construction of the bio-latrine, from the firewood it used to consume, the school was emitting an estimated 1,844,640.00 kg per of Carbon Dioxide per year. Presently, the school is emitting 1,229,760 kg per year, implying that installation of the bio-latrine will indeed contribute to reducing deforestation and forest degradation in the Miombo woodlands of western Tanzania, the main objective of the SFM project.